Intensional logic

Intensional logic is a cover term for those extensions of propositional logic and predicate logic in which truth and reference are construed relative to possible worlds, moments of time, or contexts. Modal logic and temporal logic are the two most important instances of intensional logic. Modal logic studies the logic of possibility and necessity, and temporal logic studies the logic of time by means of tense operators. In Montague Grammar an intensional logic is used in which a formal distinction can be made between the extension and intension of an expression.